Gamabufotalin, a bufadienolide compound from toad venom, suppresses COX-2 expression through targeting IKKβ/NF-κB signaling pathway in lung cancer cells

Mol Cancer. 2014 Aug 31;13:203. doi: 10.1186/1476-4598-13-203.

Abstract

Background: Gamabufotalin (CS-6), a major bufadienolide of Chansu, has been used for cancer therapy due to its desirable metabolic stability and less adverse effect. However, the underlying mechanism of CS-6 involved in anti-tumor activity remains poorly understood.

Methods: The biological functions of gamabufotalin (CS-6) were investigated by migration, colony formation and apoptosis assays in NSCLC cells. The nuclear localization and interaction between transcriptional co-activator p300 and NF-κB p50/p65 and their binding to COX-2 promoter were analyzed after treatment with CS-6. Molecular docking study was used to simulate the interaction of CS-6 with IKKβ. The in vivo anti-tumor efficacy of CS-6 was also analyzed in xenografts nude mice. Western blot was used to detect the protein expression level.

Results: Gamabufotalin (CS-6) strongly suppressed COX-2 expression by inhibiting the phosphorylation of IKKβ via targeting the ATP-binding site, thereby abrogating NF-κB binding and p300 recruitment to COX-2 promoter. In addition, CS-6 induced apoptosis by activating the cytochrome c and caspase-dependent apoptotic pathway. Moreover, CS-6 markedly down-regulated the protein levels of COX-2 and phosphorylated p65 NF-κB in tumor tissues of the xenograft mice, and inhibited tumor weight and size.

Conclusions: Our study provides pharmacological evidence that CS-6 exhibits potential use in the treatment of COX-2-mediated diseases such as lung cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amphibian Venoms / chemistry
  • Animals
  • Bufanolides / pharmacology*
  • Carcinoma, Non-Small-Cell Lung / drug therapy*
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cell Line, Tumor
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Humans
  • Lung Neoplasms / drug therapy*
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology
  • MAP Kinase Signaling System / drug effects*
  • Mice
  • Neoplasm Transplantation
  • Phosphorylation / drug effects
  • Promoter Regions, Genetic / drug effects
  • Protein Conformation
  • Xenograft Model Antitumor Assays

Substances

  • Amphibian Venoms
  • Bufanolides
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • bufotalin